The invention relates to digital communications. The invention also relates to data encryption and data compression.
Use of the airwaves for digital communications is increasing rapidly. Cellular telephones have become widely accepted for voice communications and continue to grow in popularity. Very Small Aperture Terminals (VSATs), with their 24" dish antennae, are increasingly being used for distributing software. Even smaller (18 inch) dish antennae, coupled with integrated receiver/decoder units, are being used for receiving digital television signals. Soon, all portable computers will be equipped with wireless modems for transmitting data over the airwaves.
Security and piracy are of great concern whenever data is transmitted over the airwaves, or any other public access medium. It is relatively simple to intercept a digital signal and steal the information being transmitted.
Security is of special concern to those people conducting business over public access media. Care must be taken to protect credit card numbers, engineering drawings, business letters, access codes and other types of confidential information.
Piracy is of special concern to software and multimedia developers and publishers. Piracy, involving the unauthorized copying and distribution of copyrighted software and multimedia content, robs the software developers of their time, money and energy in creating their software. Piracy also robs the publishers of their money spent in preparing the software for distribution. Uncompressed software files, especially multimedia files, are typically too large to be distributed in any practical manner. A large part of the cost of preparation is devoted to compressing the video and audio data for distribution and storage. Software pirates can bypass this cost.
Security can be provided, and piracy thwarted, by encrypting data prior to transmission and decrypting the transmitted data following transmission. Two well known encryption/decryption techniques are RSA and DES. Both techniques involve the use of encryption/decryption keys. RSA uses two keys: a public key for encryption and a private key for decryption. DES uses a single key for encryption and decryption.
Problems exist with the encryption and decryption of data. If a private key or a DES key is published, the security of the system is defeated. A subscriber might not intend to publish the key, but might do so inadvertently. A less innocent scenario can arise if an unauthorized user logs onto the computer and learns the key. Yet another scenario can arise when a computer is receiving a download over the Internet. The party making the download might make an unauthorized side trip into the host computer's hard drive and access data, including the encryption key.
In addition, hardware for encryption/decryption does not protect compressed software. Dedicated decryption chips decrypt the transmissions and provide the compressed data to a decoder or decompression system, but offer no protection for the compressed data. Because compressed data holds greater value than uncompressed data, pirates have great incentive to pirate the compressed data.
Therefore, an objective of the present invention is to protect compressed data from being pirated.
A further objective of the present invention is to increase security of data transmissions.
Another objective of the present invention is to ensure the integrity of software running on a computer participating in transactions with a server, such as in financial transactions.